Often, off-road trucks are subjected, during their routine use, to weight loads which differ greatly because of different material density and/or the ability of some material to more tightly pack when loaded into the truck body. As a result, truck bodies which are always filled to their full volume capacity may carry weight loads which exceed the capacity of the truck. Repeated occurrences of overloading result in the premature deterioration of the structural integrity of the truck, thus requiring repair or replacement of parts before anticipated.
Off-road trucks have truck bodies which are opaque and mounted on the truck at a level which makes visual inspection on the interior of the truck impossible without actually climbing to a level higher than the truck body sides. Accordingly, it is difficult to determine when the weight capacity of the truck has been reached even when it is known that the material being loaded will exceed the weight capacity if loaded to the truck body's full volume. Ordinarily, the trucks are loaded to their full volume capacity since it is only after full volume capacity is reached that there is any visual indication as to the degree of volume loading in the truck (i.e., material can be observed above the side wall of the truck bed).
Because of the inconvenience of clumsy and sometimes dangerous climbs on the side of a truck in order to peer inside the truck body, there is little assurance that the users of such off-road trucks will monitor the weight capacity of the truck, as opposed to the volume capacity of the truck. Moreover, in an era when getting the job done quickly and efficiently is stressed, there is little incentive to take the additional time required to ensure the truck is not weight overloaded.
Finally, climbing to a level high enough to visually inspect the volume of the contents in the truck body, involves some degree of risk and also tends to slow down operations. Requiring the stationing of an observer to monitor the level of loading raises the possibility of the observer falling from his or her perch or being injured by moving equipment as the truck body is filled.
The users of off-road trucks are left with the choice of either taking considerable risk and expense by stationing someone in a position high enough to look into the truck body, or ignoring the truck's weight capacity and loading the truck body to full volume on every load; or, as a third alternative, operating the truck inefficiently by estimating the weight loading of the truck and stopping the loading of the truck body when the weight capacity is guessed to be achieved.